Wireless charging devices (e.g., systems) may convert electrical energy into an electromagnetic wave form of energy to wirelessly transfer the energy as a load without a transmission line.
Wireless charging may be mainly classified into a charging type using electromagnetic induction and a charging type using magnetic resonance. The electromagnetic induction type charging technique is a method of charging a battery while a charging pad and two coils of an electronic device generate an induced current, and the magnetic resonance type charging technique is a method of performing charging by transmitting power to a transmitting/receiving end, which is 1 to 2 meter (m) away, at the same frequency.
The magnetic induction type charging technique, which is one of the wireless charging techniques, is a method of transferring power using a magnetic field induced in a coil, and may supply energy as a load by making an induced current flow in a receiving coil using a magnetic field generated by a current that flows in a transmission coil. There are standards of the magnetic induction type including wireless power consortium (WPC) and power matters alliance (PMA), etc. The WPC may use a power transmission frequency of 110 to 205 kilohertz (kHz), and the PMA may use a power transmission frequency of 227 to 357 kHz or 118 to 153 kHz.